make-dissectors-reg: optimize by factoring out the loops

Instead of calling the grep/sed pipelines for each file, build the
list of files in the beginning and call each pipeline only once,
passing the list to the first grep.

This results in a massive speedup in Cygwin; in my test, the time
it takes to run make-dissector-reg . dissectors packet-*.c in dissectors/epan
is reduced from ~116 to ~3 seconds. I also tried it on NetBSD, where
the time do to the same goes from ~6 to ~0.5 seconds.

Amend makefile comments to elide mentions of invoking multiple processes
per file.

Change-Id: Iad441e7d2b6cc3669dada57646e2f8f6b987fd34
Reviewed-on: https://code.wireshark.org/review/2826
Reviewed-by: Anders Broman <a.broman58@gmail.com>

1 files changed, 36 insertions, 80 deletions

diff --git a/tools/make-dissector-reg b/tools/make-dissector-reg
index d28793e1d5..72e896d0b2 100755
--- a/tools/make-dissector-reg
+++ b/tools/make-dissector-reg
@@ -27,6 +27,22 @@ fi
 #
 # All subsequent arguments are the files to scan.
 #
+files=''
+
+for f in "$@"
+do
+	# This won't work if any filenames contain spaces.
+	# However, this script is called by make, which doesn't support
+	# spaces either.
+	if [ -f "$f" ]
+	then
+		files="$files $f"
+	else
+		files="$files $srcdir/$f"
+	fi
+done
+
+
 rm -f ${outfile}-tmp
 echo '/* Do not modify this file.  */' >${outfile}-tmp
 echo '/* It is created automatically by the Makefile. */'>>${outfile}-tmp
@@ -54,26 +70,11 @@ EOF
 	#
 	# Build code to call all the protocol registration routines.
 	#
-	for f in "$@"
-	do
-		if [ -f $f ]
-		then
-			srcfile=$f
-		else
-			srcfile=$srcdir/$f
-		fi
-		grep '^proto_register_[a-z_0-9A-Z]* *(' $srcfile 2>/dev/null | grep -v ';'
-	done | sed -e 's/^.*://' -e 's/^\([a-z_0-9A-Z]*\).*/  {extern void \1 (void); \1 ();}/' >>${outfile}-tmp
-	for f in "$@"
-	do
-		if [ -f $f ]
-		then
-			srcfile=$f
-		else
-			srcfile=$srcdir/$f
-		fi
-		grep '^void proto_register_[a-z_0-9A-Z]* *(' $srcfile 2>/dev/null | grep -v ';'
-	done | sed -e 's/^.*://' -e 's/^void \([a-z_0-9A-Z]*\).*/  {extern void \1 (void); \1 ();}/' >>${outfile}-tmp
+	grep '^proto_register_[a-z_0-9A-Z]* *(' $files 2>/dev/null | grep -v ';' \
+		| sed -e 's/^.*://' -e 's/^\([a-z_0-9A-Z]*\).*/  {extern void \1 (void); \1 ();}/' >>${outfile}-tmp
+
+	grep '^void proto_register_[a-z_0-9A-Z]* *(' $files 2>/dev/null | grep -v ';' \
+		| sed -e 's/^.*://' -e 's/^void \([a-z_0-9A-Z]*\).*/  {extern void \1 (void); \1 ();}/' >>${outfile}-tmp
 else
 	cat <<"EOF" >>${outfile}-tmp
 #include "register.h"
@@ -84,26 +85,11 @@ EOF
 	#
 	# Build code to call all the protocol registration routines.
 	#
-	for f in "$@"
-	do
-		if [ -f $f ]
-		then
-			srcfile=$f
-		else
-			srcfile=$srcdir/$f
-		fi
-		grep '^proto_register_[a-z_0-9A-Z]* *(' $srcfile 2>/dev/null | grep -v ';'
-	done | sed -e 's/^.*://' -e 's/^\([a-z_0-9A-Z]*\).*/  {extern void \1 (void); if(cb) (*cb)(RA_REGISTER, \"\1\", client_data); \1 ();}/' >>${outfile}-tmp
-	for f in "$@"
-	do
-		if [ -f $f ]
-		then
-			srcfile=$f
-		else
-			srcfile=$srcdir/$f
-		fi
-		grep '^void proto_register_[a-z_0-9A-Z]* *(' $srcfile 2>/dev/null | grep -v ';'
-	done | sed -e 's/^.*://' -e 's/^void \([a-z_0-9A-Z]*\).*/  {extern void \1 (void); if(cb) (*cb)(RA_REGISTER, \"\1\", client_data); \1 ();}/' >>${outfile}-tmp
+	grep '^proto_register_[a-z_0-9A-Z]* *(' $files 2>/dev/null | grep -v ';' \
+		| sed -e 's/^.*://' -e 's/^\([a-z_0-9A-Z]*\).*/  {extern void \1 (void); if(cb) (*cb)(RA_REGISTER, \"\1\", client_data); \1 ();}/' >>${outfile}-tmp
+
+	grep '^void proto_register_[a-z_0-9A-Z]* *(' $files 2>/dev/null | grep -v ';' \
+		| sed -e 's/^.*://' -e 's/^void \([a-z_0-9A-Z]*\).*/  {extern void \1 (void); if(cb) (*cb)(RA_REGISTER, \"\1\", client_data); \1 ();}/' >>${outfile}-tmp
 
 fi
 echo '}' >>${outfile}-tmp
@@ -119,52 +105,22 @@ WS_DLL_PUBLIC_DEF void
 plugin_reg_handoff(void)
 {
 EOF
-	for f in "$@"
-	do
-		if [ -f $f ]
-		then
-			srcfile=$f
-		else
-			srcfile=$srcdir/$f
-		fi
-		grep '^proto_reg_handoff_[a-z_0-9A-Z]* *(' $srcfile 2>/dev/null | grep -v ';'
-	done | sed -e 's/^.*://' -e 's/^\([a-z_0-9A-Z]*\).*/  {extern void \1 (void); \1 ();}/' >>${outfile}-tmp
-	for f in "$@"
-	do
-		if [ -f $f ]
-		then
-			srcfile=$f
-		else
-			srcfile=$srcdir/$f
-		fi
-		grep '^void proto_reg_handoff_[a-z_0-9A-Z]* *(' $srcfile 2>/dev/null | grep -v ';'
-	done | sed -e 's/^.*://' -e 's/^void \([a-z_0-9A-Z]*\).*/  {extern void \1 (void); \1 ();}/' >>${outfile}-tmp
+	grep '^proto_reg_handoff_[a-z_0-9A-Z]* *(' $files 2>/dev/null | grep -v ';' \
+		| sed -e 's/^.*://' -e 's/^\([a-z_0-9A-Z]*\).*/  {extern void \1 (void); \1 ();}/' >>${outfile}-tmp
+
+	grep '^void proto_reg_handoff_[a-z_0-9A-Z]* *(' $files 2>/dev/null | grep -v ';' \
+		| sed -e 's/^.*://' -e 's/^void \([a-z_0-9A-Z]*\).*/  {extern void \1 (void); \1 ();}/' >>${outfile}-tmp
 else
 	cat <<"EOF" >>${outfile}-tmp
 void
 register_all_protocol_handoffs(register_cb cb, gpointer client_data)
 {
 EOF
-	for f in "$@"
-	do
-		if [ -f $f ]
-		then
-			srcfile=$f
-		else
-			srcfile=$srcdir/$f
-		fi
-		grep '^proto_reg_handoff_[a-z_0-9A-Z]* *(' $srcfile 2>/dev/null | grep -v ';'
-	done | sed -e 's/^.*://' -e 's/^\([a-z_0-9A-Z]*\).*/  {extern void \1 (void); if(cb) (*cb)(RA_HANDOFF, \"\1\", client_data); \1 ();}/' >>${outfile}-tmp
-	for f in "$@"
-	do
-		if [ -f $f ]
-		then
-			srcfile=$f
-		else
-			srcfile=$srcdir/$f
-		fi
-		grep '^void proto_reg_handoff_[a-z_0-9A-Z]* *(' $srcfile 2>/dev/null | grep -v ';'
-	done | sed -e 's/^.*://' -e 's/^void \([a-z_0-9A-Z]*\).*/  {extern void \1 (void); if(cb) (*cb)(RA_HANDOFF, \"\1\", client_data); \1 ();}/' >>${outfile}-tmp
+	grep '^proto_reg_handoff_[a-z_0-9A-Z]* *(' $files 2>/dev/null | grep -v ';' \
+		| sed -e 's/^.*://' -e 's/^\([a-z_0-9A-Z]*\).*/  {extern void \1 (void); if(cb) (*cb)(RA_HANDOFF, \"\1\", client_data); \1 ();}/' >>${outfile}-tmp
+
+	grep '^void proto_reg_handoff_[a-z_0-9A-Z]* *(' $files 2>/dev/null | grep -v ';' \
+		| sed -e 's/^.*://' -e 's/^void \([a-z_0-9A-Z]*\).*/  {extern void \1 (void); if(cb) (*cb)(RA_HANDOFF, \"\1\", client_data); \1 ();}/' >>${outfile}-tmp
 fi
 echo '}' >>${outfile}-tmp
 if [ "$registertype" = plugin ]